大花紫薇和‘丹红紫叶’紫薇杂交F_(1)代不育细胞学分析

Cytological studies of F_(1) hybrid sterility between Lagerstroemia speciosa and Lagerstroemia indica ‘Ebony Embers’

【目的】大花紫薇和‘丹红紫叶’紫薇子代高度不育,为了解析其子代不育的机理。【方法】本试验以大花紫薇作母本和‘丹红紫叶’紫薇作父本的杂交F_(1)代‘潇湘华秀’为材料,通过石蜡切片显微技术观察其雌雄蕊的生长发育过程及成熟花粉粒中的可溶性糖、淀粉、脂类物质的积累情况;并对3种紫薇花蕾不同生长发育阶段的可溶性糖含量、淀粉含量、游离脯氨酸含量进行分析测定。【结果】1)‘潇湘华秀’不育是雄性不育和雌性不育共同作用形成的,其花粉存在干瘪、畸形、大小不均等异常现象,绝大部分花粉不能萌发。2)与大花紫薇和‘丹红紫叶’紫薇相比,F_(1)代在减数分裂时期发生异常,具体表现为减数分裂时,有部分染色体无法正常联会并排布到赤道板中央,染色体不均匀分离,发育成异常的二分体、带微核二分体、带微核四分体、五分体、六分体,且大部分花粉细胞核在二核期消解,成熟花粉粒大部分畸形,无内含物且不能萌发,可萌发的花粉粒为2n花粉粒。3)大孢子在四分体时期萎缩消解,后期形成有少量胚囊痕迹的空洞。4)F_(1)代花蕾的可溶性糖、淀粉、游离脯氨酸含量都低于同等时期的亲本花蕾,且大部分花粉中未观测到脂类、可溶性糖和淀粉积淀。【结论】染色体行为异常导致异常四分体的出现和二核花粉粒时期细胞核的解体是花粉败育的主要原因;四分体时期大孢子萎缩消解是雌性不育的主要原因。

【Objective】The progeny of Lagerstroemia speciosa and Lagerstroemia indica ‘Ebony Embers’ are highly sterile,In order to analyze the reasons for the sterility of their offspring.【Method】In this experiment,L.indica ‘Xiaoxiang Huaxiu’ was used as the material which was the F_(1) hybrid of L.speciosa as the female parent and L.indica ‘Ebony Embers’ as the male parent,by paraffin section microscopy to observe the growth and development process of the stamens and pistils of male,and the mature pollen grains in the accumulation of soluble sugar,starch,lipid;and the contents of soluble sugar,starch,free proline in different growth stages were determined.【Result】1) The sterility of L.indica ‘Xiaoxiang Huaxiu’ was the result of combined male and female sterility.Pollen grains exhibit aberrant characteristics including shriveled appearance,deformities,and size variations,leading to the majority of pollen grains being unable to germinate.2) Compared with L.speciosa and L.indica ‘Ebony Embers’,abnormalities occurred in the F_(1) generation during meiosis,specifically,some chromosomes were not arranged normally to the center of the equatorial plate during meiosis,and the chromosomes segregation was not uniform,developing into abnormal dyads,micronucleated dyads,micronucleated tetrads,pentads and sexads,and most pollen nuclei dissolve during the binucleate pollen grains stage.Mature pollen grains were mostly deformed without contents and couldnot sprout,the germinable pollen grains were 2n pollen grains.3) The megaspore atrophies and dissolved in the tetrad stage,and formed a cavity with a few embryo sac traces in the later stage.4) The contents of soluble sugar,starch and free proline in F_(1) generation’s flower bud were lower than those in the parent’s flower bud of the same period.Lipid,soluble sugar and starch accumulation was not observed in most pollen.【Conclusion】The abnormal behavior of chromosomes leads to the appearance of abnormal tetrads and the disintegration of nuclei in the period of binucleate pollen grains are the main reasons for pollen abortion.Atrophy and disintegration of megaspore during tetrad is the main cause of female sterility.